Lawrence, Ernest Orlando

Lawrence, Ernest Orlando

(b. Canton, South Dakota, 8 August 1901; d. Palo Alto, California, 27 August 1958)

physics.

Lawrence was the elder son of Carl Gustav Lawrence, a Wisconsin-born educator whose father, Ole Hundale Lavrens (also a teacher), emigrated from Telemark in Norway to the Wisconsin Territory in 1846. His mother, Gunda Jacobson Lawrence, was also a teacher and of Norwegian ancestry. Lawrence’s father was a graduate of the University of Wisconsin who successively served as city, county, and state superintendent of public education in South Dakota, and in 1919 became president of a teacher’s college.

As a boy, Lawrence attended public schools in Canton, South Dakota, and in Pierre, the state capital. His best friend was Merle A. Tuve, another teacher’s son who also became a well-known physicist (he measured, with Gregory Breit, the height of the ionosphere in 1925). Lawrence finished high school at sixteen and attended Saint Olaf College, a small Lutheran college in Northfield, Minnesota, on a scholarship for a year. He transferred to the University of South Dakota, where he first became interested in physics under the guidance of the professor of electrical engineering, Lewis E. Akeley, who recognized his student’s unusual aptitude for science. After graduating with high honors in 1922, Lawrence enrolled at the University of Minnesota for postgraduate studies, mainly at the urging of Merle Tuve, who had preceded him to Minneapolis.

After earning a master’s degree at Minnesota under the direction of W. F. G. Swann with an experimental confirmation of the theory of induction in an ellipsoid rotating in a magnetic field, Lawrence followed Swann to the University of Chicago, where he came into contact with A. A. Michelson, H. A. Wilson, Leigh Page, Arthur Compton, and Niels Bohr. In 1924 Lawrence followed Swann to Yale, where he completed his doctoral dissertation, a study of the photoelectric effect in potassium vapor. He remained at Yale as a research fellow and then assistant professor, quickly gaining a reputation as a brilliant experimenter, mainly in photoelectricity.

In 1928, at twenty-seven, Lawrence was offered an associate professorship at the University of California in Berkeley and startled fellow physicists by accepting—exchanging a famous old university for a little-known state university in the Far West. Its subsequent world renown as a center of research was due to a considerable extent to the primacy of its physics faculty, which came to rank with those of Cambridge and (in an earlier day) Göttingen among the world’s finest. That phase began with the tenure of Lawrence and his contemporaries, among whom were Samuel Allison, R. B. Brode, and J. R. Oppenheimer. Within two years Lawrence, at twenty-nine, had become a full professor.

With his first graduate students, Niels E. Edlefsen and M. Stanley Livingston, Lawrence developed his invention of a circular accelerator, later called the cyclotron, in the shape of a flat circular can cut in two

along a diameter and placed inside a vacuum chamber. A high-frequency oscillator is connected between the two D-shaped halves, and charged particles are introduced near the center. The particles are constrained to travel in a circular path by a magnetic field along the axis of the can. With proper synchronization, the oscillating field serves to impart successive accelerations to each particle as it repeatedly crosses the boundary between the two halves, sending it on an ever-widening path with increasing velocity as it spirals outward. When it approaches the wall, it can be deflected through an opening toward a target, which it hits with a high velocity, producing nuclear disintegrations. Lawrence conceived the idea after seeing the illustrations for an article by the Norwegian-born engineer Rolf Wideröe elaborating a linear, rather than a circular, acceleration scheme proposed by the Swedish physicist Gustaf A. Ising.

The cyclotron was the first in a family of circular particle accelerators that made high acceleration energies available with relatively small instruments. Once the principle was proved, progress was swift. The unavailability of a sufficiently strong magnet was an obstacle that Lawrence characteristically overcame by persuading the Federal Telegraph Co. to donate an eighty-ton iron core originally intended for a radio arc generator but no longer needed. With this magnet and a cyclotron chamber 27.5 inches in diameter, Lawrence and his associates were able to produce energies of millions of electron volts. This achievement ushered in the era of high-energy physics and made possible the disintegration of atomic nuclei, artificial isotopes, and the discovery of new elements. Biomedical applications include radioactive tracers and uses in cancer therapy. One of the first results of major importance, the disintegration of lithium, was achieved at Berkeley as early as 1932, that annus mirabilis of modern physics which also saw the earlier disintegration of lithium by John Cockcroft and E. T. S. Walton, and the discovery of deuterium by H. C. Urey, of the neutron by James Chadwick, and of the positron by C. D. Anderson, each later honored by a Nobel Prize. In addition to lithium, many heavier nuclei were disintegrated in the Berkeley cyclotron, which was unique in that respect—no other machine could then do it. These disintegrations proved that nearly every nuclear reaction takes place if there is sufficient energy for it, a result of great importance in the development of nuclear physics. They also permitted accurate determination of the binding energy of various nuclei and, by comparison of the measured reaction energies (the masses were measured in a mass spectrograph), a complete verification of Einstein’s law relating energy and mass.

World renown followed quickly. Lawrence was invited to his first Solvay Congress at thirty-two, was elected to the National Academy of Sciences at thirty-three, became director of his Radiation Laboratory at thirty-five, and in 1939 received the Nobel Prize, the first American associated with a state university to do so. (He had already received, in 1937, the Comstock Prize of the National Academy of Sciences and the Royal Society’s Hughes Medal.) He was named director of what became known as the Radiation Laboratory (“Rad Lab”) at Berkeley.

Lawrence was one of the American physicists who helped set up another “Radiation Laboratory” at the Massachusetts Institute of Technology in 1940; but that name disguised the laboratory’s real function, the development of centimetric radar. He actively recruited young scientists for the laboratory but did not go himself, for with America’s entry into World War II, an even larger project appeared on the horizon; the “Manhattan Project” to develop a nuclear or “A” (atomic) fission bomb.

Fearful that German scientists might be the first to develop such a weapon, other scientists, let by refugees from Nazism, proposed such a development to the U.S. government. The Berkeley Rad Lab, and Lawrence and Oppenheimer personally, were destined to play major roles in these endeavors. The Rad Lab helped devise a method of obtaining fissionable materials. A thirty-seven-inch cyclotron was converted into a mass spectograph for the purpose. The electromagnetic separation method devised at Berkeley was later used in a large laboratory (known as Y–12) at Oak Ridge, Tennessee, which provided the separated U²³⁵ for the Hiroshima atomic bomb. Oppenheimer became director of the laboratory at Los Alamos, New Mexico, where the first bombs were produced.

In 1945, with World War II ended by fission bombs dropped on Hiroshima and Nagasaki, the Rad Lab returned to predominantly scientific pursuits, including the construction of a 184-inch cyclotron (actually a new type of accelerator, the synchrocyclotron, based on a principle formulated by E. M. McMillan). The Los Alamos Scientific Laboratory, still managed by the University of California, continued in weapons research. Lawrence was actively involved in the subsequent controversy about the advisability of developing another, more destructive weapon, the thermonuclear-fusion or “H” (hydrogen) bomb. Its advocates (among whom the Hungarian-born physicist Edward Teller was the most prominent) prevailed. Oppenheimer was against it, and his long friendship with Lawrence ended over their deep disagreements on the desirable defense posture of the United States. The final break came when Oppenheimer, in a cause célèbre lost the security clearance he needed as a government consultant.

In addition to the laboratory at Los Alamos, a second laboratory for research on nuclear weapons was started at Livermore, California, under the sponsorship of Lawrence and Edward Teller. This laboratory was at first a branch of the Rad Lab. Research at the Berkeley site was limited to basic science. During these years, larger and more efficient accelerators were designed and constructed there, and for a long time the Rad Lab had the highest energies and a near-monopoly of the type of results depending on them. Machines that could accelerate particles to energies of billions of electron volts (BeV—hence the name of one of them, the “bevatron”) were constructed. It was by means of the bevatron that the antiproton was discovered by Emilio Segrè and Owen Chamberlain, and the properties of mesons were explored in detail, which led to a general understanding of strongly interacting particles. Lawrence also created the style of “big science”; large-scale physics started in Berkeley and set the pattern around the world in such later organizations as the Brookhaven National Laboratory in New York, the Centre Européen Pour la Recherche Nucléaire (CERN) in Switzerland, and the National Accelerator Laboratory in Illinois. Lawrence remained personally involved throughout and suffered no lessening of his inventive genius (among other devices, he invented a novel type of color television tube at this time); but increasing demands on him as a government and industrial consultant often took him away from Berkeley. Amount these endeavors was his participation, at the request of President Eisenhower, in the Conference of Experts to Study the Possibility of Detecting Violations of a Possible Agreement on Suspension of Nuclear Test in Geneva in the summer of 1958. It proved to be his last contribution. Exhausted and plagued by recurrent ulcerative colitis, he was flown home for an operation, which he did not survive.

Lawrence married Mary (Molly) Kimberly Blumer, daughter of the dean of Yale’s medical faculty, in 1932; he had first met her when she was a schoolgirl of sixteen. They had two sons and four daughters. He was very close to his younger brother John, a physician who was associated with him professionally as director of a biophysics laboratory founded at Berkeley for the purpose of exploiting biomedical applications of nuclear physics. Another close associate was E. M. McMillan, who succeeded to the directorship of the Rad Lab. Several other associates achieved great prominence, including Luis Alvarez, Owen Chamberlain, Glenn Seaborg, and Emilio Segrè each of whom later received a Nobel Prize, as did McMillan.

Lawrence’s name is commemorated in the two Rad Lab sites, now known as the Lawrence Berkeley Laboratory and the Lawrence Livermore Laboratory; and in the Lawrence Hall of Science, a Berkeley museum and research center devoted to the improvement of science education. Annual Lawrence Awards are given to young scientists honored by the U.S. Atomic Energy Commission (AEC), and the transuranium element 103, discovered at Berkeley, was named Lawrencium. Lawrence was a member of the National Academy, of Sciences, a foreign member of the Swedish Academy, an honorary member of the Soviet Academy, and the recipient of countless honorary degrees and another awards from institutions all over the world.

BIBLIOGRAPHY

I. Original Works. A complete list of Lawrence’s publications follows the article by Luis W. Alvarez in Biographical Memories. National Academy of Sciences, 41 (1970), 251-294. Lawrence’s papers are in the Bancroft Library on the Berkeley campus of the University of California.

II. Secondary Literature. A biography commissioned by the University of California and based on hundreds of interviews and a large store of written materials is Herbert Childs, An American Genius; The Life of Ernest Lawrence (New York, 1968). Lawrence’s role in the beginnings of the atomic age is described in several book-length studies, among which vol. I of the AEC-sponsored history by R. G. Hewlett and O. E. Anderson Jr., The New World: 1939-1946 (New York, 1962), id the most detailed. There are also journalistic accounts, not uniformly flattering to Lawrence, such as those by Robert Jungk, Heller als tausend Sonnen (Stuttgart, 1956), trans, by James Cleugh as Brighter Than a Thousand Suns (New York, 1960); and Nuel Pharr Davis, Lawrence and Oppenheimer (New York, 1968).

For an authoritative account of the development of the cyclotron, see M. Stanley Livingston, “History of the Cyclotron (Part I),” in Physics Today, 12 (Oct. 1959), 18-23; and Edwin M. McMillan (Part II), ibid., 24-34.

Charles SÜsskind